Better HbA1c during the first years after diagnosis of type 1 diabetes is associated with residual C peptide 10 years later

OBJECTIVE: To identify the factors associated with residual C peptide production at least 10 years after diagnosis in children and adolescents with type 1 diabetes. RESEARCH DESIGN AND METHODS: 73 children and adolescents (<25 years), born in 1988–2005, diagnosed with type 1 diabetes were included during the 4-year study period (2013–2016). At least 10 years after diagnosis, we measured any remaining C peptide concentration using an ultrasensitive C peptide ELISA (≥1.17 pmol/L). The average hemoglobin A1c (HbA1c) was calculated during each of the 10 years after diagnosis and further grand average was calculated for the entire study period. RESULTS: C peptide was detectable in 38% of participants. The C peptide concentration was 4.3±5.3 pmol/L. At onset of type 1 diabetes, participants were on average approximately 5 years of age, and their average HbA1c was 9.4% (79 mmol/mol). During the first 3 years after diagnosis, HbA1c was lower in the group with detectable C peptide at follow-up ≥10 years later. Moreover, detectable C peptide was more common among female participants. Body mass index SD scores had not increased since the 1-year follow-up, but were higher in patients with measurable C peptide. Nine participants (12%) had been diagnosed with celiac disease and two (3%) with hypothyreosis. Eighteen (25%) participants had retinopathy. CONCLUSIONS: Children and adolescents with detectable C peptide after more than 10 years of diabetes duration were predominantly female and had better HbA1c than others during the first 3 years after diagnosis.